This dictionary maps between ODF style family names and the
tag prefixes they use. This is currently a duplicate of the same
dictionary in Styles2CSS. Here only the style family names are used
as keys in the StyleTree that is generated.
Defined in: StyleTree.js.

On webkit, which has the ability to style scrollbars
with CSS, `window` has the property 'ontouchstart'.
This can be used as a hint of touch event support,
and we can take advantage of that to decide to show
custom scrollbars (because webkit hides them).
Defined in: ZoomHelper.js.